Dr Sean Barrett (Imperial College London)

Dr Dan Browne (UCL)

Topological quantum error correction and quantum memories

Quantum information is encoded in real physical systems, which can become lost or corrupted through imperfect control operations or unwanted, unavoidable interactions with the surrounding environment.

 I am investigating the thresholds and overheads required to store quantum information in a topological quantum error correction code, known as the toric code. This allows two qubits of information to be stored in a lattice of physical qubits, where the redundancy of the scheme allows for error correction.

 For an infinite lattice, if errors error rates are small, the error correction procedure certainly succeeds, whereas if errors occur with a probability above some threshold value, the error correction procedure certainly fails. I am examining the behaviour of the code in a more realistic situation: the finite lattice.

 The goal of this project is to use a Monte Carlo study to find a reliable way to determine the required lattice size in order to encode information with a desired fidelity, for known error rates. This has applications to both quantum memories, where information is stored and also to related schemes which can be used as a full error-tolerant quantum computer.


In addition to my EPSRC studentship, I have recently won a $10,000 award for credit on the AWS – Amazon’s web-based computing resource to support my research.